I see AvWeb are reporting the probable demise of the diesel C182.
There is now no definite timeline for the C182 diesel according to the article. It also mentions Cessna are taking out the diesel engines from the aircraft already fitted with them, sending these engines back to the manufacturer and re fitting avgas engines.
There's speculation as to why this has happened, suggestions are that it's due to partly economics (avgas being to cheap) and reliability problems with the engines.
See article here
Has Cessna Suddenly Grown Cold On Diesel? - AVweb Insider Article